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I love distance-based sampling. Quick and often very effective. There have been numerous innovations and developments associated with the estimation of density, spatial pattern, and other important attributes of distribution. The flexibility depending on underlying dispersion patterns has also significantly evolved.

Protocol (t-square)
1. Run out parallel transects perpendicular to the longest axis of your study site.
2. Estimate relative distances & dispersion patterns prior to detailed sampling.
3. On each transect, measure the distance from regular points on transect to nearest shrub (x) then from that shrub to the next nearest shrub moving in the same direction (y), i.e. do not go backwards hence the t-square nomenclature.
4. Select appropriate regular intervals within a transect to ensure that you do not sample the same shrubs.
5. Consider alternating sides of transect.
6. Disperse transects similarly to ensure representative, non-overlapping coverage of study site.
7. Sample at least 150 shrubs to effectively estimate dispersion and approximately 100 for density.
8. Georeference the start and end point of every transect.
9. Use these data to calculate density, dispersion, and explore size-classes of shrubs.
10. Select appropriately blocked variation from with site for animal surveys associated with the shrubs relative to non-canopied sites.

Foundation species effect estimation
(a) For each shrub, record height, widest canopy dimension, and minimum canopy dimension to be able to estimate shrub volumes.

(b) At each shrub, use a small quadrat to record all species present and total abundance.

(c) At each shrub, record animal activity/presence signs.

Full details of the basics of this distance-based sampling listed in these publications